Yahoo caught up with director Joss Whedon on the red carpet of the Iron Man 3 premiere where it seems he dropped a huge clue as to who might be appearing in the upcoming Avengers movie.

"I've got these two characters, two of my favorite characters from the comic book, a brother-sister act, they're in the movie. That's exciting! You lock certain things in, there's a fluidity."

Most people when they think of members of the Avengers who are brother and sister, they think of the mutants Scarlet Witch and Quicksilver, the children of Magneto.

Now for those wondering if Quicksilver and Scarlet Witch would be off limits to Whedon because they are mutants and therefore would fall under the X-Men rights currently belonging to 20th Century Fox, this is what Marvel Studios President Kevin Feige said in a recent interview with HeyUGuys:

"They're uh - Itís a little complicated, but if they want to use them in an X-Men movie they could, and if we want to use them in an Avengers movie we could. They're unique,"

So let us know what you think, would you like to see Scarlet Witch and Quicksilver join the Avengers in the next movie?